Abrasive wheel



June 24, 1930. H. F. SKILLINGS 1,767,321

ABRAS IVE WHEEL Filed April 16, 1928 In veniqifl HavoZdFSi/Z s,

y am wgw gg for illustrative purposes,

Patented June 24, 1930 UNITED STATES PATENT OFFICE HAROLD F. SKILLINGS,OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOS TO THE BLAN- CHABD MACHINECOMPANY, OF CAMBRIDGE, MASSACHUSETTS, 'A CORPORATION OF MASSACHUSETTS IABRASIVE WHEEL Application filed April 1c, 1928. Serial no. 270,461.

by rivets 10 extending through both walls and through the partitions.

This invention relates to a novel and improved abrasive wheel, of theclass in which several blocks or segments of abrasive matedivide theannular groove 9 into a series of rial are adjusta-bly and removablymounted arcuate chambers for theabrasive blocks new in the chuck orholder, in which they-may be to be described. adjusted from time to timeas they wear Each of the chambers receives a pair of away, andmayfinally be removed and reabrasive blocks or segments 11", which, inthe placed by new ones. present example, are arcuate,that is to say,

The invention will be best understood by they are convexly curved ontheir facesto I} reference to the following description, when taken inconnection with the accompanyin are elm e circumferentially see Fig. 2),and o hl y gare required; This reduces Fig. 1 is an elevation of anabrasive wheel the cost of manufacture of the wheel, and inexemplifyingthe invention; creases the strength of the blocks against lat- Fig. 2 isa of the same as viewed *eral stress orinward thrust of the work as thefrom below; latter is passed across the face of the wheel.

Fig. 3 is a sectional View, on an enlarged In the present'example, theends of each scale, on line 3-3 of Fig; 2; and block are rounded as at12, thereby to give 7 F lg. 4 isa sectional view on line 44 of them afair bearing, and to make them selfaligning, as will presently appear.Each of the partitions 6 has two curved seats or bearbodiment .of theinvention which is selected ing surfaces 13 for the adjacent ends of thethere is shown an blocks. These seats and the ends of the blocksabrasive wheel comprisingabody 5, which in are formed on arcs struckfrom centers A. practice is a steel forging, herein annular Eachseat-13, therefore, constitutesafulcrum, in form, intended to be mountedon a face on which the block may be rocked aboufi'an plate to be securedto the spindle of a grlnfllaxis represented by the point A in Fig. 2.111g machine, such as a vertical splndle sur- In lik ann r, th oth r endof each block face grinder. is rounded as at 12, on an arc struck fromThe body presents a plurality of abutthe point B. Between the adjacentends 12' Inentsti, herein three, equally spaced part1 f h i f bl k th ri rovid d xtions, and an outer Wall 7, herein anH pansive'means to urgesuch blocks, respectivedisposed about said abutment-s. In the presl i ojt 'di ti' n a ain t th abut ent example, the body presents also aninner wall 8, herein annular, and separated from the outer wall by anannulargroove' 9. The

In the drawings:

i teferring to the drawings, and to the empurposes :first, itstrengthens the body and'f-contacts with a shoe 15, having an areshapedseat 13'; which fits the end of the block, and is formed on an arcstruckfrom top, down to the bottom of the body before the point B as acenter.

the water flies outwardly. This helps to keep dirt'out of the chuck, andto bring the Wa er suitable means for forcing the shoes 15 apart, nearerto the wheel face. Herein, the abutthe same in the present exam 1ecomprising ments or partitions 6 are formed as sepaa wed e 16, havingupwardly converging rate pieces, inserted between the inner and faces 1which enga corresponding com 00 outer walls, and suitably secured inplace, as verging faces on the Engagement of 1 Referring now to Fig. 3,there is providea. ea,

the shoes with the wedge isconveniently maintained by a U-shaped spring18, having arms 19 suitably secured to the shoes, as by providing thelatter with slots 20, in which the arms are secured by screws 21.

The shoes are forced apart in opposition to the spring by appropriatemeans,'herein a screw 22, threaded into a block 23, and extendingloosely through a much larger opening 2a provided in the wedge 16, whichis also chambered out as at 25, to receive a head 26 and an annularshoulder or collar 27 on the screw. The inner end of'this chamber thusprovides a seat against which the thrust of the collar 27 may be exertedto cause the wedge to be moved in an upward direction, and to force theshoes apart when the screw is rotated in the proper direction by theapplication of a socket wrench to the head 26.

The described operating mechanism is held in place, and isprevented-from dropping out by securing the block 23 to the body 5. Thisis conveniently accomplished in the present example by the provision ofa screw 28 (see Fig. 4) extending loosely through a hole 29 provided inthe body, and threaded into the block 23, the head of the screw beingreceived in a chamber 30 counterbored into the body. The block alsoconstitutes a convenient means for holding the spring 18 in place, saidblock for this purpose being provided in its upper end with a shallowroove 31, which receives the base of the spring. The shoes and the wedgeconstitute a floating assembly capable of movement radially andcircumferentially, considered with reference to the axis of the body.

Referring now to Fig. 2, the blocks of each pair may be likenedto twolinks constituting a toggle, and the expansible assembly may be cnsidered as a toggle-actuating mechanism, capable of swinging theadjacent ends of the blocks in an outward direction against the stop orlimiting means presented b the outer annular wall 7. In Fig. 2, thepoints A and B, representing the pivotal axes at the ends of one block,have been connected to each other by a line AB, while the points'B havebeen-connected to each other by a line 13-13. In expanding the operatingmechanism, the line B-B naturally lengthens, as a consequence of whichthe links represented by the lines A-B, A-B, swing outwardly about thepoints A. At the same time, the expansible mechanism urges the blocksagainst the seats presented by the abutments 6. While the movement ofthe shoe 15 actually is tangential, the large angle subtended by eachblock is such that there is an outward componentof the force tending topress the outer surface of the block firmly into contact with the innercircumferential surface of the surrounding wall. Naturally, this isaugmented by the action of centrifugal force when the wheel is rotating.

The structure is characterized by a symmetrical formand arrangement ofthe several segments or blocks, and corresponding forces. Inasmuch asthe ends of the blocks are rounded, there is no tendency to chip orbreak away, as there would be if they were angular. Moreover, this formofthe blocks is advantageous because, as already stated, they are selfaligning. One factor in this is the employment of the shoes between theblocks and the wedgewhich forces them apart. The rubbing action of thewedge against the shoes introduces very little frictional resistance,while the rubbing of the ends of the blocks against the arc-shaped seats13 and 13 is so slight as to be negligible.

The blocks are held so firmly that no positive stop is required behindthem to keep them from being pushed back into the wheel body, after theyhave been worn away to such an extent as to require adjustment in anoutward direction, it being understood, of course, that new blocksextend the full depth of the annular groove in the body. While it isossible to introduce s acers, such as bloc s of wood or metal, behindthe segments, this is found to be unnecessary in practice. As theclamping and centrifugal forces are considerable, it is quite probablethat there-is distortion of the outer wall 7 sufficient to make itscurvature agree with the curvature of the segments, provided thereshould be any slight difference initially.

Having thus described one embodiment of my invention, but withoutlimiting myself thereto, what I claim and dsire by Letters Patent tosecure is:

1. In an abrasive wheel, the combination of a body having inner andouter, annular walls and an intermediate, annular groove; a plurality ofpartitions connecting said walls to each other at intervals and dividingsaid groove into a plurality of arcuate chambers, each partitionpresenting on each side thereof an arc-shaped abutment; a plurality ofarcuate, abrasive segments arranged in pairs, one pair in each chamber,each segment having ,two arc-shaped ends, each "resting a ainst one ofsaid arc-shaped abutments; each segment having an arc-shaped surfaceengaging said outer annular wall; and" expansible means between the twoadjacent ends of the segments of each pair, each expansible meansincluding two shoes, each presenting an arcshaped abutment which engagesthe adjacent, arc-shaped end of one of said segments; a wedge betweenand engaging said shoes, 9. U- shaped spring secured to said body andhaving two arms secured to said shoes, respectively, and tending to movethem toward each other, and a screw for moving said wedge relatively tosaid shoes to force them apart. 1

2. In an abrasive wheel, the combination of a body having inner andouter annular wedge between and rock said walls and an intermediateannular groove; being between and contacting'with two ful a plurality ofpartitions connecting said walls to each other at intervals anddividingsaid groove into a plurality of arcuate chambers; a lurality of arcuateabrasive blocks arrange in pairs, one pair in each chamber, each blockhaving one end resting against one of said partitions; and expansiblemeans two adjacent ends of the blocks each. expansible means includbetween the of each pair, ing two shoes engaging such adjacent ends, a

screw said shoes to force them apart and to urge the other ends of saidblocks against said parti-r tions, and to urge said outer wall, andspring maintain engagementof said intervening wedge.

3. In an abrasive wheel, the combination of a body having inner andouter, annular walls and an intermediate, annular groove a plurality ofpartitions connecting said walls to each otherat intervals and dividingsaid groove into a plurality of arcuate chambers, each partitionpresenting two oppositely facing fulcrums; a plurality of arcuate,abrasive segments arranged in pairs, one pair in each chamber, mountedto rock on oneof said fulcrums and an arc-shaped surface engaging theinner cirblocks against. said shoes with the cumferential surface ofsaid outer, annular" wall and expansible means between two adjacent endsof the segments of each pair to rock said segments on their fulcrumsoutwardly toward said outer wall.

4:. In an abrasive of a bod having an annula'r'wall and a plurality ofulcrums within the circle of said wall; a plurality of abrasivesegments, each having rocking contact with one of said fulcrums andadapted to engage the inner circii'mferential surface of said wall; aplurality of shoes, each having rocking contact with one of saidsegments; a plurality of wedges each contacting with one of said shoes;and a plurality of wedge-actuating screws for callsing said wedges toact through said shoes to blocks, respectively, ward said fulcrums.

6. In an abrasive wheel, the combination of a body presenting aplurality of fulcrums and a wall about said fulcrums; a plurality ofabrasive blocks arranged in pairs, each pair engaging said shoes, 21-for moving said wedge relatively. to-

means tending to.

each segment having an end wheel, the combination abutments; and

segments on their fulcrums outcrums and with said wall; and expansiblemeans between and having pivotal connection with two adjacent portionsof the blocks of each pair to rock such blocks on their fulcrums and tourge such blocks, respectively, in opposite directions against said twofulcrums and outwardly againstsaid wall, I

7. In an abrasive wheel, the combina'ticu'of a body presenting aplurality of-fulc'rums;

a: plurality of abrasive blocks arranged-in being between twofulcr'ums';

pairs, each pair and expansible means between two adjacent portions ofthe blocks "of-each pair to rock such blocks such blocks,

tions toward and aIwedge between said shoes.

blocks arranged" in shoes apart. a 1 g 9. In an abrasive wheel, thecombination of on their fulcrumsga'nd to urge respectively, in oppositedirec"- said 'fulcrums,"said expans'ible means including two shoes:havingipivotal 1 connection with said portions, respectively,

11 an abrasive wheel, the'combinatio'n of a body presenting a pluralityof abutment's';

between-='twoabutof the blocks of i each pair, yielding means tendin'gto "move" said shoes'together; and means to I'H'OVG'Slid a bodypresenting a plurality of abutments a plurality of abrasive blocksarrangedin pairs; between two abutments'ytwo respectively, with two adeach pair being shoes contacting, jacent surfaces of the blocks of eachpair, yielding means tending to move said shoes together; and a'wedgescrew tomove said shoes apart.

10 In an abrasive wheel, the combination of a rotatable bodypresenting'a plurality of abutments; a plurality of abrasive blocksarranged in pairs, each pair being between two expansive means betweentwo adjacent surfaces of the blocks of each pair to urge them apart,said means including shoes contacting with said surfaces, yield- 'lIigmeans tending to move said shoes together, wedges between the shoes ofeach pair and movable lengthwise of theaxisof rota tion of said body,and wedge-actuating screws extending lengthwise of said axis.

11. In an abrasive wheel, thecombination of a rotatable body presentingaplurality of abutments; a plurality of abrasive blocks ar ranged inpairs, each pair being between two abutments; andexpansive'means betweentwo adjacent surfaces of the blocks of each pair to urge them apart,said means including shoes contacting with" said surfaces, a U- shapedspring having two arms connected to said shoes and tending to move saidshoes together', wedges between the shoes of each pair and movablelengthwise of the axis of rotation of said body,

arms of each spring, means securing said and wedge operating blocksbetween theblocks and said springs to said body, and wedge-actuatingscrews extending lengthwise of said axis and having screw-threadedengagement with said blocks, respectively.

12. In an abrasive wheel, the combination of a body presenting aplurality of abutments constituting fulcrums, a plurality of abrasiveblocks arranged in pairs, each pair being between two abutments andconstituting a toggle; means to swing the blocks of each pair in anoutward direction about their fulcrums; and means to limit suchswinging.

13. In an abrasive wheel. the combination of a body resenting aplurality of abutments constituting fulcrums, a plurality of abrasiveblocks arranged in pairs, each pair being between two abutments andconstitutin a toggle; means between two adjacent en s of t e blocks ofeach pair to swing the blocks of each pair in an outward direction abouttheir fulcrums; and means to limit such swinging.

14. In an abrasive wheel. the combination of a body presenting aplurality of abutments constituting fulcrums; a plurality of abrasiveblocks arranged in pairs, each pair being between and contacting withtwo abutments and constituting a toggle; expansible means between twoadjacent ends of the blocks of each pair to urge said blocks, resectively, in opposite directions against said abutments and to swingsaid blocks in an outward direction about their fulcrums: and means tolimit the outward swinging of said blocks.

15. In an abrasive wheel, the combination of a body presenting aplurality of abutments constituting fulcrums; a. plurality of abrasiveblocks arranged in pairs, each pair being between and contacting withtwo abutments and constituting a toggle; expansible means between twoadjacent ends of the blocks of each pair to urge said blocks,respectively, in o posite directions against said abutments an to swingsaid blocks in an outward direction about their fulcrums; and a wallabout said blocks to limit their outward swinging movement.

16. In an abrasive wheel, the combination of a body presenting aplurality of abutments constituting fulcrums; a plurality of abrasiveblocks arranged in airs, each pair being between and contacting with twoabutments and constituting a toggle; and expansible means between twoadjacent ends of the blocks of each pair to exert a pressure againstsaid ends and to operate said toggle.

17. In an abrasive wheel, the combination of a body presenting aplurality of abutments each having an arc-shaped seat constituting afulcrum; a plurality of abrasive blocks arranged in airs, each pairbeing between two seats an each block having an arc-shaped end seated inone of said areshaped seats; and expansible means between two adjacentends of the blocks of each pair to exert a pressure against such ends.

18. In an abrasive wheel, the combination of a body presenting aplurality of abutments each having an arc-shaped seat constituting afulcrum; a plurality of abrasive blocks arranged in pairs, each pairbeing between two'seats and each block having an arc-shaped end seatedin one of said arcshap'ed seats, the remaining pairs of ends of saidblocks being arcshaped; and operating means between the remaining pairsof ends, said operating means including shoes having arc-shaped seats inwhich such remaining ends are seated.

19. In an abrasive wheel. the combination of a body presenting aplurality of abutmcnts each having an arc-shaped seat constituting afulcrum; a plurality of abrasive blocks arranged in pairs, each pairbeing between two seats and each block having an arc-shaped end seatedin one of said areshaped seats. the remaining pairs of ends of saidblocks being arc-shaped; shoes having arc-shaped seats in which suchremaining ends are seated, and means between said shoes to urge themapart.

20. In an abrasive wheel, the combination of a body presenting aplurality of abutments each having an arc-shaped seat constituting afulcrum; a plurality of abrasive blocks arranged in pairs, each pairbeing between two seats and each block having an arc-shaped end seatedin one of said areshaped seats; the remaining pairs of ends of saidblocks being arc-shaped; shoes having arc-shaped seats in which suchremaining ends are seated, and a wedge and wedge-operating screw betweenthe shoes of each pair to urge them a art.

21. An abrasive element for use in a chuck of the class describedcomprising a block of abrasive material having two parallel fiat faceseither of which constitutes a grinding face, two parallel cylindricsurfaces whose common axis of generation is perpendicular to said fiatfaces. and two non-parallel cylindric surfaces whose axes of generationare parallel with each other and perpendicular to said flat faces, saidnon-parallel cylindric surfaces being each tangent to both of saidparallel cylindric surfaces.

22. An abrasive element for use in a chuck of the class describedcomprising a block of abrasive material having two parallel fiat faceseither of which constitutes a grinding face, two parallel cylindricsurfaces whose common axis of generation is perpendicular to said flatfaces, and two non-parallel cylindric surfaces whose axes of generationare between such surfaces and are parallel with each other andperpendicular to said flat faces, said non-parallel cylindric surfacesbeing each tangent to both of said parallel cylindric surfaces.

23. An abrasive element for use in a chuck of the class describedcomprising an arcuate block of abrasive material having a fiat facewhich constitutes a grinding face, and two cylindric surfaces whose axesof generation (ill H ROLD F. SKILLINGS.

